Overload device



May 29, 1923. 1,457,109

\ H. E. FROST OVERLOAD DEVICE I lun/Enma MQW May 29, 1923. 1,457,109

H. E. FROST OVERLOAD DEVI CE Filed Aug. l, 1921 2 Sheets-Sheet 2 INVENTOP` Pstsnte'd May 29, 1923.

'UNITED STATES Parri-:1W oFFlcE.

HOHER E. FROST, CLEVELAND, OHIO, ASSIGNOR TO THE ELECTRIC CONTROLLER & MANUFACTURING COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

OVERLOAD DEVICE.

Application filed August 1, 1921. Serial No. 488,990.

T allwhomztmay concern.' y Be it known that I, HOMER E. FRosT, a citizen of the United States, residing at Cleveland in the county of Cuyahoga and l State of hio, haveinvented new and useful Improvements in Overload Devices, of which the following is a specification.

My invention relates to overload devices for electric motors, and more particularly l0 for alternating current motor systems which have voverload devices with a heatexpansive wire in each of two of the phases in 2-phase or 3-phase systems. If the overload device is designed to be tripped by the action of separate springs for balancing the pulls of the expansive wires, the operation of the overload device by a single phase current in one wire (the other wire being operative Ifor any reason) requires conslderably more current than whe'n the operation of the overload device is caused by the expansive action of both wires. It is the object of this invention to provide means whereby such an overload device as described may be tripped by the employment of a-single vspring or by the application of spring tension at a single point without the disadvantages attending the use of a separate spring for each expansion wire. The objects of this invention will be better understood in connection with the following description.

On the accompanying drawings, Fig. 1 'is a side elevation of an overload device embodying the principles of my invention; Fig. 2, a bottom plan view of Fig. 1 with some of the parts omitted; Fig. 3, a view of the upper part of Fig. 1; Fig. ,4, a sectional detail showing the rear member of the tripping device; Fig. 5, an enlarged de tail looking at the right hand end of Fig. 3, Fig. 6, a detail of the tripping mechanlsm 1n the position in which it is when the circuit is open; Fig. 7, a diagrammatic view of the circuits which may accompany my device; and Fig. 8, a diagram showing the efficiency of my invention.

On the drawings 1 indicates an insulating basecomposed of'slate, for example. 2 and 3 are heat-expansive wires severally connected at one end to the metal blocks 6 and 7 slidably seated in the respective forks 4 and 5, and adj ustably held therein by the nuts 8 and 9 which bear on the outer edges of the forks. The remaining ends of the wires 2 and 3 are respectively connected to the ends of the operating levers 10 and 11, both pivoted on the pin or pivot 12 supported by the base 1. Fach lever is composed of an outer member 13 and an inner member 14 connected together at their upper ends by a pin 15. To the pins 15 the wires 2 and 3 are respectively attached. The levers 10. and 11 have inwardly pro jecting tripping fingers 16 and-17, respectively, formed by projections from their members 13 and 14. The projections of each pair of members are connected together by a spacing pin 18. The members 13 of the levers have below the projections 16 and 17 holes to loosely receive the end necks 19 of the equalizing pin or bar 20, which has central between the necks 19 the neck 21 to which one end of the operating spring 22 is attached, the other end thereof being connected to the post 23 secured to the` base 1.

24 is a switch-tripping lever comprising the 'back member 25 and the front member 26, both pivoted on the pivot 27 secured to the base 1. The members are connected together by the pin 28. The lower end ofv the member 25 is engaged by the spacing pin 18 of the lever 11, and the lower end of the lever member 26 is engaged by the spacing pin 18 of the lever 10, as shown best in Fig. 5. A switch-reset springv29 tends to keep the lower ends of the members 25 and 26 in contact with the fingers 16 and 17. The upper end of the member 25 has the fork members 30 and 31, between which is the fixed post 32 acting as a stop for the fork members and as a support for the bellcrank lever 33 pivoted on the outer end thereof, and having the arms 34 and 35.v An overthrow spring 36 connects the arm 34 to the upper end of the member 26, the spring lyingtol the ri ht of the lpivot post 32 when the arm 35 isghorizontal. The arm 35 is connected by the link 36 of insulating material to the free end of the lever 37 carried by the pivot 38 below the link. The pivot 39, which connects the link to the lever 38, also carries the rocking line, as shown on Fig. 1.

` represent the cores ofthe transformers.

`in Fig. 7.

contact 40, having its upper end arran ed to en age the fixed contact or post 41 w 4en the link andj'the'arm (which "are togglemembers) 'are in a" substantially straight The lower end of the lever is connected-to the spring 42 which allowsthe contact 40 to have a wiping action on the contact 41.- The contact 41 is connected by the lead 43 to the terminal44, and the pivot 38 is connected by the lead 45 to the terminal 46. i

The ends of' the expansive wire 2 are connected by the wires 47 and 48 to the secondary Winding 53 of the transformer 49, and the ends of the expansive wire 3 'are connected by the wiresl 50 and 51 "to' the secondary winding 54 ofthe-transformer 52. The primary winding 55 "of the transf former 49has the terminals 56"'and`57,` and the primary 'winding 58 of the transformer- 52 has the terminals 59 and 60. 61 and-62 Referring now to 7, `the terminals 56 4and 59 are fconnected to the'v two terminals 63 and 64`ofthe'" alternating currentmotor 65. I`'rThe terminals 57 and 60 are connected to `the movable switch r.members 66 and 67 of the switch 68. Theftliird motor terminal 69 is connected' to the mov- 'able switch member 7()r The said switch members`| 'are pivotally connected to s' the operatingbar 71, actuated" by the switchoperating wir'idingl 72 to close the switch members "66, 67 ,and 70 on their liXed lconlftacts, 73, 74 and 75, and actuated by the spring 76 -to open'the said switch members whenthewinding 72 is (le-energized. `.The contacts 73,174 and 75 are connected to the source .of alternating current supply by the supply wires 77, 78 and 79. The lwinding .72 is connected in the circuit of the neutral lcontact 75 and in one of the o'uter wires, as 77,l through the'handswitchv 80 and the parts 37, 438, 40 and 41, as shown fOn Fig.' 8'the equalizer 27 is represented as applied directly to the wires ,2 and 3 at thelpoints a4 andb, these' indicating the position of the equalizer when the wires2 andY 3 are co'ldl Thecorresponding point-of application 'of the5 spring 22 is indicated by'uthe letter c. a andb indicate the position fof the equalizer 27 when vbbtlthe tion L -b',"the'point` of application ofthe spring 22 being at'b. 1*-

y the spring has been reduced to 6 lbs.. Then the pull at a and b will be reduced to" 3 lbs. each. If the wire 2 is out of circuit, .the point a will remain stationary while the point b will move to b', the point c moving to o, at which point the spring exerts a pull of only 10.5 lbs. divided between the points a and b. The pull at l5 will be som'ewhat in excess. of' 5.25 lbs., owing to the movement of the point c of the application vfoi" the spring 22 slightly toward the point 162-" The necks of the equalizer bar 27 cause -a Ieadjustnrient ofthe points of application when the bar moves from lthe position am?) 'tdthe diagonal position -b, so that the power of the spring on the point b is greater than on the point a, Thus, the spring which cexerts a pull of-only 3 lbs. on each wire when both wires are equallyheated, exerts apull of more than 5.25 lbs. onone heated wire, as 3, when theothergwire, as 2, is open if circu'ited. Thisv means V'that .thezheated wire 3 isstretched suiiiciently totrip the switch contact' 40before the wire 3 is heated to such a high temperatureas wouldfhave been re- A guired if both wires were heated equally. I" separate springs. were employed, each pulling l7.5'lbs. at the'fpoints a and b, and the wire 2 was out of circuit, the spring acting on'the point a would still exert a' pull of 7 .5 lbs. while ythe spring actingon the point 5 would exert a pull of 3 lbs., a loss 'of 2.25 lbs. over the pull "exerted at the point b When 'only one spring is pulling at 'the point o.

l Referring particularly to Fig. 7, if the switch 8() is closed, the single phase current in the winding 72 will cause thevswitches 66, i

67 and,70 to engage the contacts 73, 74 and 75, thereby connecting the neutral wire 79 to the motor terminal 69, while the outer wires 77 and 78 are connected to the remaining motor terminals 63 and 64 through the primary windings of the transformers 49 and-52. When'the contacts 40 and 41 'are l opf'ened,y the winding 72' is de'energi.zed,'per f mittig'the spring 76 to open the switches 66,'f67`and 70 and cause the motor 65 .to stop.

Al lever 10 '0r the lever 11 or .bothfthe'spring 36 passes from the v'right sid'eofzth'ey 'fulcrum 32 of the lever 33 tothe'leit side thereof, thereby'causing the latter to move lquickly from the position shown in Fig. 1 to thatI shown in Fig. 6 where thetoggle-membersl 35, 36', havepulled-the lever 37l to the left enough to open rthecontacts 40 and 41.

I have 'shown'myinvention in connection *As the upper 'end 'of the lever 24 vis moved to the left in Fig. 1 by the-actionofthe with a threefwi alternating current sys? tem, but it is evident that it is applicable to other multiphase systems.

By varying the gradient of the spring 22, it ispossible to vary the relative amounts of current required for single and multiphase operations. v

I claim- K 1.v In Aan .overload device for alternating current' systems, two expansive wires, one m each of two phases, an overload switch controlling the openin o f the circuit of the wires, Iand neans orv tripping the switch when' either or both of the wires expand a predetermined distance, "but with less consumption of current when one wire is open eircuited. l

2. In an 'overload device for alternating current Systems, two expansive wires, one in each of two phases, an overload switch controlling the opening of the circuit of the wires, and means including a single spring for trippingthe switch when either or both of the wires ex land a predetermined distance, but with ess consumption of current when one wire is open circuited.

3. In an overload devicefor alternating current systems, two expansive wires, one in each of two phases, an equalizer ba'r, means loosely connecting its "ends to the wires, a spring connected to the central portion of the bar. and o rating'to'move the bar as one or both wires expand, and an overload of the cir' cuit of the and tripped y the move ment of either or both ends of the bar a predetermined distance during the expansion of one or both wires.

4. In anoverload device for alternating current systems, two expansive wires, one in each of two phases, a lever having one end attached to an end of one wire, a lever having one end attached to an end of the other wire, an equalizer bar arranged transversely of the levers and having its ends loosely connected `to the remaining ends of the levers, a spring connected to the central portion of the bar and operating to move the bar as one or both wires expand, and an overload switch controlling the opening of the circuit of the wires and 'tripped by the movement of either or both ends of the bar apredetermined distance during the expansion of one or both wires. v

' 5. In an overload device for alternating current systems, two expansive wires, one in each of two phases, an equalizer bar having end and lcentral necks, means. loosel connecting the end necks` with the wires, a spring connected to the central neck and operating .to move the bar as one or. b oth wires expand, and an overload switch controlling the opening of the. circuit of the Wiles and trip d by the movement of either .or both ends o the bar a predetermined distance during the expansion of one or both lwires. l Signed at Cleveland, Ohio, ,this29th day 'ofJuly, 1921. v

E. FROST. 

